It casts some new light on the paper's interception of voicemail messages on the mobile phone of Milly Dowler, the 13-year-old who was abducted and murdered in 2002.

According to the WSJ, while police were hunting for the girl, the News of the World "scrambled at least eight reporters and photographers to an Epson ink cartridge factory... hoping to land a big scoop: missing Milly Dowler found alive."

The paper was confident that they would find her there because of its eavesdropping of her phone messages.

Though it was a false lead it culminated, says the Journal, in the publication on 14 April 2002 "of the only articles containing discussions of the girl's voicemails printed by the News of the World." The WSJ continues:

"A close look at News of the World's quest for Milly Dowler scoops in 2002 sheds fresh light on the crisis that is shaking News Corp today.

This amounts to an explicit acknowledgment that the tabloid targeted her phone for illegal hacking. The company hasn't released that person's name."

The Journal then deals in detail with key differences in three stories published in separate NotW editions on 14 April, the outline of which were reported in yesterday's Observer.

Version one: published in the News of the World's earliest editions

To illustrate the differences, the WSJ publishes cuttings (reproduced here) that show significant alterations between the story published in early editions and two others carried in later editions.

The first edition story - published on page 9, bylined Robert Kellaway, and headlined "Milly 'hoax' riddle" - began:

"The hunt for missing Milly Dowler took a new twist last night when it emerged that messages has been sent to her mobile phone after she vanished. One of them appeared to be offering her a job in the Midlands."

It went on to quote the message itself: "Hello Mandy. We are ringing because we have some interviews starting. Can you call me back? Thank you. Bye Bye."

It also mentioned two other messages, including a strange one left by a man who said, "Mortlake in Putney by Tangies" and signed off "Piggo baby".

Version two: on page 30

However, none of this detail was published in the stories published in the NoTW's later editions. The second version, which appeared on page 30 and was bylined Sarah Arnold, was headlined: "New Milly mystery"

The intro was exactly the same as before. But this story focused instead on the possibility that a hoaxer had been posing as Milly and was therefore hampering the police investigation.

It contained just one passing reference to a voicemail message.

Version three: new headline

Then, in the final edition, came a third version, also on page 30, also bylined Sarah Arnold, but headlined "Missing Milly 'hoax' outrage: Sick woman has posed as youngster." It began:

"The hunt for missing Milly Dowler took a shocking twist last night when it emerged a deranged woman has been posing as the missing youngster.

Police believe the sick hoaxer called into a recruitment agency pretending to be Milly."

Citing "a person familiar with the matter," the WSJ says that News International discovered the differences in the three versions last month and passed the information to Scotland Yard.

It was three days before publication, on 11 April, that NotW staff were sent to the Epson ink factory. Reporters were told by news desk executive Neville Thurlbeck of a tip that Milly was working there. The reporters weren't told the tip's source.

Thurlbeck refused to comment on the claim to the Journal. He was arrested in April by Scotland Yard on suspicion of unlawfully intercepting voicemail messages. He has not been charged.

One of the Epson stakeout participants told the Journal that the team thought the tip was "a wild goose chase," given that Milly was just 13. But staff monitored the factory exits for three days until Thurlbeck called them off.

According to the Journal, neither Kellaway nor Arnold could recall writing the stories under their bylines. The paper says:

"Former News of the World staffers say it wasn't unusual for the News of the World's editors to put a reporter's byline on a story not written by that person.

In fact, one reporter whose name appeared on hundreds of News of the World stories over the years — Edward Trevor — doesn't actually exist, former staffers say."